Personal care compositions are important products for most consumers. Personal care compositions, and sunscreen compositions in particular, contain a variety of additives that provide a wide array of benefits to the composition. Emollients are among the additives commonly used in personal care compositions to aid in moisturization of the skin, and in particular prevent and treat dry skin, protect sensitive skin, improve skin tone and texture, and mask imperfections. Emollients can increase skin hydration or act as a barrier to prevent trans-epidermal water loss (“TEWL”). It is also important for emollients to provide a desirable sensory feel to keep the skin in a smooth and supple condition, without suffering from negative aesthetic qualities, such as greasiness or stickiness. In sunscreen compositions, however, achieving such beneficial moisturization and sensorial feel properties while boosting SPF and UV absorption can be difficult.
Oil-free skin care products were originally developed to avoid using substances with high comedogenic potential, such as mineral oil, petrolatum, esters, and triglycerides. Many oil-free products in the skin care market do not contain hydrophobic ingredients, which may provide short term skin hydration, but lack the benefit of a barrier to TEWL. Emulsion-type oil free compositions have typically utilized silicone fluids, for example as disclosed in U.S. Pat. No. 5,380,528, although such compositions are generally considered to be sensory modifiers with poor performance as a barrier to TEWL. Another consideration surrounding the use of silicone fluids is the acknowledged need to replace such components due to environmental and health related issues.
Oil-free polyalkylene glycols have also been disclosed in personal care compositions. For example, U.S. Pat. No. 4,511,554 discloses an antiperspirant stick composition having a low staining potential, which contains a mixture of polyoxyethylene(25)propylene glycol stearate and a polyoxypropylene, polyoxyethylene ether of a long chain fatty alcohol. However, the prior art does not disclose a polyalkylene glycol according to the present invention which gives superior results as an oil-free skin care emollient.
Consequently, there is a need to develop new oil-free emollient compositions for use in sunscreen compositions, including sunscreen boosters which will help achieve a high SPF (sun protection factor) and high UVA absorption while improving moisturization and hydration of skin in conjunction with desirable aesthetic and sensorial properties.